Secondary motions of the shoulder during arm elevation in patients with shoulder tightness

An analysis of secondary shoulder motions (humeral rotation, humeral head anterior/posterior translation, scapular tipping, and scapular upward/downward rotation) in subjects with anterior/posterior shoulder tightness provides the opportunity to examine the role of tightness as a means of affecting shoulder motions. Subjects with shoulder tightness (anterior, n = 12; posterior, n = 12) elevated their arms in the scapular plane. Three replicated movements were performed to the maximum motions. Kinematics data were collected by FASTRAK 3D electromagnetic system. To determine if a significant difference of the secondary motions existed between anterior/posterior shoulder tightness, two-factor mixed ANOVA models with the repeated factor of elevation angle (five elevation angles) and the independent factor of group were calculated. The relationships between the self-reported functional scores (Flexilevel Scale of Shoulder Function, FLEX-SF) and abnormal shoulder kinematics were assessed. For humeral head anterior/posterior translation, the subjects with posterior tightness demonstrated anterior humeral head translation (10 mm, p = 0.019) compared to subjects with anterior tightness. The subjects with anterior tightness demonstrated less posterior tipping (2.2°, p = 0.045) compared to subjects with posterior tightness. The humeral anterior translation had moderate relationships with FLEX-SF scores (r = ?0.535) in subjects with posterior tightness. The scapular tipping had moderate relationships with FLEX-SF scores (r = 0.432) in subjects with anterior tightness. In conclusion, the secondary motions were different between subjects with anterior and posterior shoulder tightness. During arm elevation, less scapular posterior tipping and less posterior humeral head translation in subjects with anterior and posterior shoulder tightness, respectively, are significantly related to self-reported functional disability in these subjects.     

Biomechanical model of the human shoulder joint--II. The shoulder rhythm

A method to investigate the rhythm of the human shoulder, i.e. the interplay between the motion of constituent parts of the shoulder, has been devised and tested. The method is based upon numerical evaluation of low dose roentgenstereophotogrammetric motion pictures of subjects equipped with radiation dense implantations in the bones. Evaluation of the method shows that it may be used in determining motion patterns and that the employed interpolation techniques can be used to simulate motions not actually performed in the laboratory. The shoulder rhythm has been previously poorly investigated and quantified results published pertain to one plane only. Our results on motion patterns correlate with previous investigations. With this method, we show that the absolute position of the bones varies significantly between individuals while the relative displacement of the bones during motion exhibit similarities. In particular the results show that, under normal conditions, the individual rhythm is very stable and insensitive to small hand-loads.     

Analysis of glenoid fixation for a reversed anatomy fixed-fulcrum shoulder replacement

The restoration of pain-free stable function in gleno-humeral arthritic cases in various situations such as rotator cuff deficiency, old trauma and failed total shoulder arthroplasty is a challenging clinical dilemma. The Bayley-Walker shoulder has been designed specifically for very difficult cases where surface replacement devices do not provide sufficient stability. This device is a fixed-fulcrum reverse anatomy implant where the centre of rotation is placed medially and distally with respect to the normal shoulder, to increase the lever arm of the abductor muscles. An important problem in devices of this type is obtaining secure and long-lasting fixation of the glenoid component. In this design, fixation is achieved using a tapered screw for engagement with cortical bone and HA coating for subsequent osseointegration. This study presents the results from a three-dimensional finite element analysis conducted on this component for two load cases at 60 degrees and 90 degrees abduction. The results showed that most of the forces were transmitted from the component to the cortical bone of the scapula, the remaining load being transmitted through cancellous bone. Histology from a retrieved case shows evidence of bone remodelling. The retrieval case obtained some time after implantation showed new bone formation had occurred around the threads onto the HA coating. Fixing the component in this way at multiple locations in cortical bone may overcome the problems of glenoid loosening historically associated with cemented constrained devices.     

Morphometric affinities of the human shoulder.

A recent discussion by Corruccini and Ciochon ('76) implies that previous multivariate morphometric studies of the shoulder, reviewed in Oxnard ('73), have been misinterpreted because due allowance was not made for the overall sizes of the specimens. Results that were given functional significance in the earlier investigations are cited as being due at least in part to overall bodily size. Although examination of the range of genera selected for mention by corruccini and Ciochon seems superficially to support this view, it is demonstrated here that examination of the full range of genera in the earlier studies refutes, unequivocally, that suggestion. The discussion by Corruccini and Ciochon ('76) also implies that the more complex size correction applied in their study produces a result different from that of the previous workers. Again, although perusal of the particular part of the earlier study selected for discussion by Corruccini and Ciochon would appear to bear that out, it is demonstrated here that comparisons with all parts of the earlier results provide a different picture. Thus the main result of Corruccini and Ciochon replicates rather closely a more restricted part of the earlier result not mentioned by Corruccini and Ciochon. The difference between Corruccini and Ciochon's principal result and the main result of the prior authors is shown to rest upon the difference between the more restricted earlier study of "residual" shoulder dimensions and the other broader studies; i.e., not upon any multivariate manipulation, but upon the inclusion in the broader study of a wider range of information about the shape of the primate shoulder. Knowledge of these and other points is important in assessing the overall contribution of the discussion of Corruccini and Ciochon.     

Quantitation of human immunodeficiency virus type 1 infection kinetics.

Tissue culture infections of CD4-positive human T cells by human immunodeficiency virus type 1 (HIV-1) proceed in three stages: (i) a period following the initiation of an infection during which no detectable virus is produced; (ii) a phase in which a sharp increase followed by a peak of released progeny virions can be measured; and (iii) a final period when virus production declines. In this study, we have derived equations describing the kinetics of HIV-1 accumulation in cell culture supernatants during multiple rounds of infection. Our analyses indicated that the critical parameter affecting the kinetics of HIV-1 infection is the infection rate constant k = Inn/ti, where n is the number of infectious virions produced by one cell (about 10(2)) and ti is the time required for one complete cycle of virus infection (typically 3 to 4 days). Of particular note was our finding that the infectivity of HIV-1 during cell-to-cell transmission is 10(2) to 10(3) times greater than the infectivity of cell-free virus stocks, the inocula commonly used to initiate tissue culture infections. We also demonstrated that the slow infection kinetics of an HIV-1 tat mutant is not due to a longer replication time but reflects the small number of infectious particles produced per cycle.     

Quantitation of pharyngeal motor function in normal human subjects.

A need exists for accurate pressure recording of pharyngeal motor events. Results of this study indicate that accurate quantitation of pharyngeal motor activity is not possible using a water-filled catheter system, even when high infusion rates are used. An intraluminal strain gauge system, however, achieves high-fidelity recording. Quantitation of pharyngeal peristalsis using the intraluminal strain gauge system reveals peristaltic pressure amplitudes higher than those hitherto recorded. In normal subjects, peristaltic amplitude averages about 200 mmHg in the hypopharynx, complexes in one subject being as high as 600 mmHg. A zone of relatively low pressure exists in the oropharynx. Mean pharyngeal wave duration decreases progressively in an aboral direction, from 1.0 to 0.3 s, and peristaltic wave speeds range between 9 and 25 cm/s. Accurate quantitation of pharyngeal peristaltic variables provides the necessary basis for characterization and assessment of pharyngeal motor disorders.     

Estimation of distal arm joint angles from EMG and shoulder orientation for transhumeral prostheses

In this paper, we quantify the extent to which shoulder orientation, upper-arm electromyography (EMG), and forearm EMG are predictors of distal arm joint angles during reaching in eight subjects without disability as well as three subjects with a unilateral transhumeral amputation and targeted reinnervation. Prior studies have shown that shoulder orientation and upper-arm EMG, taken separately, are predictors of both elbow flexion/extension and forearm pronation/supination. We show that, for eight subjects without disability, shoulder orientation and upper-arm EMG together are a significantly better predictor of both elbow flexion/extension during unilateral ($R^2=0.72$) and mirrored bilateral ($R^2=0.72$) reaches and of forearm pronation/supination during unilateral ($R^2=0.77$) and mirrored bilateral ($R^2=0.70$) reaches. We also show that adding forearm EMG further improves the prediction of forearm pronation/supination during unilateral ($R^2=0.82$) and mirrored bilateral ($R^2=0.75$) reaches. In principle, these results provide the basis for choosing inputs for control of transhumeral prostheses, both by subjects with targeted motor reinnervation (when forearm EMG is available) and by subjects without target motor reinnervation (when forearm EMG is not available). In particular, we confirm that shoulder orientation and upper-arm EMG together best predict elbow flexion/extension ($R^2=0.72$) for three subjects with unilateral transhumeral amputations and targeted motor reinnervation. However, shoulder orientation alone best predicts forearm pronation/supination ($R^2=0.88$) for these subjects, a contradictory result that merits further study.     

Towards a model for force predictions in the human shoulder.

In this paper the concept of a three-dimensional biomechanical model of the human shoulder is introduced. This model is used to analyze static load sharing between the muscles, the bones and the ligaments. The model consists of all shoulder structures, which means that different positions and different load situations may be analyzed using the same model. Solutions can be found for the complete range of shoulder motion. However, this article focuses only on elevation in the scapular plane and on forces in structures attached to the humerus. The intention is to expand the model in future studies to also involve the forces acting on the other shoulder bones: the scapula and the clavicle. The musculoskeletal forces in the shoulder complex are predicted utilizing the optimization technique with the sum of squared muscle stresses as an objective function. Numerical results predict that among the muscles crossing the glenohumeral joint parts of the deltoideus, the infraspinatus, the supraspinatus, the subscapularis, the pectoralis major, the coracobrachialis and the biceps are the muscles most activated during this sort of abduction. Muscle-force levels reached values of 150 N when the hand load was 1 kg. The results from the model seem to be qualitatively accurate, but it is concluded that in the future development of the model the direction of the contact force in the glenohumeral joint must be constrained.     

Adaptation of scapula lateral rotation after reverse anatomy shoulder replacement

Scapula motion is significant for support of the arm and stability of the shoulder. The effect of the humeral elevation on scapular kinematics has been well investigated for normal subjects, but there are limited published studies investigating adaptations after shoulder arthroplasty. Scapula kinematics was measured on 10 shoulders (eight subjects) with a reverse total joint replacement. The measurements were performed using an instrumented palpating technique. Every subject performed three simple tasks: abduction, elevation in scapula plane and forward flexion. Results indicate that, lateral scapula rotation was significantly increased (average of 24.42% over the normal rhythm) but the change was variable. Despite the variability, there is a clear trend correlating humeral performance with increased rotation (R2 0.829). There is clearly an adaptation in lateral scapula rotation in patients with shoulder joint replacement. The reason for this is unclear and may be related to joint pathology or to muscle adaptation following arthroplasty.     

Quantitation of human anti-mouse antibody in serum by flow cytometry.

Clinical investigations utilizing murine monoclonal antibodies require techniques for the detection of the human anti-mouse antibody (HAMA) response in patient serum. We report here a flow cytometric assay for the quantitation of HAMA. Commercially available beads conjugated with goat anti-mouse antibody provide a solid phase matrix for a triple bridge immunoassay. The measurement of fluorescein labeled antibodies by flow cytometry allows accurate quantitation of the HAMA. The assay will detect antibody levels of approximately 1.0 ng/ml. Antibody recovery in serum samples with known amounts of antibody added was greater than 90% at levels greater than or equal to 10 micrograms/ml. Serum samples obtained from 41 patients prior to and after single or multidose infusions of KS1/4-Desacetyl-vinblastine were analyzed. These results were compared with HAMA titers previously determined by ELISA. With few exceptions, patients with low titers as determined by ELISA demonstrated low HAMA potencies by flow cytometry and those with highest titers the highest potencies. Patients with no detectable HAMA by ELISA were also negative by flow analysis. The results of our studies demonstrate that HAMA levels can be accurately and quantitatively determined by flow cytometry.     

Gross anatomy of the forelimb and shoulder girdle of theGalago senegalensis

The gross anatomy of the forelimb of theGalago senegalensis is described. The skeletal, muscular, nervous, and vascular systems are illustrated. TheGalago senegalensis is compared to theTarsius and other selected primates. Also examined in the study are muscle attachments and selected upper limb indices derived from measurements of bone dimensions.